9

1208 Chapter 9: Surface Modeling
Curve Properties group
These controls affect individual curves you select
in the Section Curves list, as opposed to properties
of the sweep surface in general. They are enabled
only when you have selected a curve in the Section
Curves list.
Reverse—When set, reverses the direction of the
selected curve.
Start Point—Adjusts the position of the curve’s
start point. This can help eliminate unwanted
tw ists or "buckles" in the surface.
Thiscontrolisdisabledifthecurveisnotaclosed
cur ve.
While you’re adjusting start points, a dotted
blue line is displayed between them, to show the
alignment. The surface is not displayed, so it
doesn’t slow dow n adjustment. When you release
the mouse button, the surf ace reappears.
Insert—Adds a curve to the section list. Click to
turn on Insert, then click the curve. The curve
is inserted before the selected curve. To insert a
cur ve at the end, first highlig ht the "----End-----"
marker in the list.
Remove—Removes a curve from the list. Select the
curve in the list, and the n click Remove.
Refine—Refines the 1-rail sweep surface. Click
to turn on Refine, then click an iso curve on the
surface. (As you drag the mouse over the surface,
the available section curves are highlighted.) The
curve you click is converted to a CV curve and
inserted into the sweep and the section list. As
when you refine a point curve, refining a sweep
can change the curvature of the surf ace slightly.
Once you’ve refined the surface by adding a
cross-section curve, you can use Edit Cur ves to
change the curve.
Replace—Lets you replace the selected curve.
Select a curve in the list, click this button, and then
select the new curve.
Sweep Parallel—When on, ensures that the sweep
surface’snormalisparalleltotherail.
Snap Cross-Sections—When on, cross-sect ion
curves are translated so they intersect the r ail.
The first cross sec tion is tr anslated to the start of
therail,andthelasttotheendoftherail. The
crosssectionsinthemiddlearetranslatedto
touch the rail at the closest point to the end of the
cross-section cu rves.
When Snap Cross-Sections is on, the sweep
followstherailcurveexactly.Thismakesiteasier
to construct 1-rail sweep surfaces.
Road-Like—When on, the sweep uses a constant
up-vector s o the cross sections twist uniformly
as they t ravel along the rail. In other words, the
crosssectionsbanklikeacarfollowingaroad,ora
camera following a path constraint (page 2–398).
Default=off.
When you edit the surface, you can control the
angle of banking . The up-vector is displayed
as a yellow gizmo (similar to the gizmo that
lathe surfaces (page 1–1190) useforthecenter
of rotation). To change the up-vector angle, use
Rotate (page 1–439) to change the gizmo’s angle.
Display Iso Cur ves—When set, the 1 -rail sweep’s
V-axisisocurvesaredisplayedaswellasthe
U-axis curves used to construct the loft. The
V-axis curves are only for display. You c an’t use
them for surface construction.
Edit Curves—Lets you edit the currently selected
curve without switching to another sub-object
level. ClicktoturnonEditCurve. Thepoints
or CVs of the curve are displayed, as well as the
control lattice if the curve is a CV curve. You can
now transform or otherwise change the points
or CVs as if you were at the Point or Curve CV
sub-object level. To finish editing the curve, click
to turn off Edit Curves.
Tip: When you edit curves in a 1-rail sweep,
turning off display of the sweep itself can make the